Carbazole derivative, light-emitting element material, light-emitting element, light-emitting device, electronic device, and lighting device

ABSTRACT

A carbazole derivative represented by the general formula (1) is provided. In the formula, Ar 1  represents a substituted or unsubstituted aryl group having 6 to 10 carbon atoms which form a ring; α and β independently represent a substituted or unsubstituted arylene group having 6 to 12 carbon atoms which form a ring; R 1  represents an alkyl group having 1 to 4 carbon atoms or a substituted or unsubstituted aryl group having 6 to 10 carbon atoms which form a ring; and R 11  to R 17  and R 21  to R 28  independently represent hydrogen, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 10 carbon atoms which form a ring.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a carbazole derivative. In addition,the present invention relates to a material for a light-emittingelement, a light-emitting element, an electronic device, and a lightingdevice each of which uses the carbazole derivative.

2. Description of the Related Art

In recent years, research and development have been extensivelyconducted on light-emitting elements utilizing electroluminescence. In abasic structure of such a light-emitting element, a layer containing alight-emitting substance is interposed between a pair of electrodes. Byvoltage application to this element, light emission can be obtained fromthe light-emitting substance.

Since such a light-emitting element is a self-light-emitting type, ithas advantages over a liquid crystal display in that visibility ofpixels is high, a backlight is not required, and so on. Accordingly,such a light-emitting element is considered suitable as a flat paneldisplay element. In addition, other advantages of such a light-emittingelement are that it can be manufactured to be thin and lightweight andthe response speed is very high.

Furthermore, since such a light-emitting element can be formed into afilm form, planar light emission can be easily obtained by forming alarge-area element. This feature cannot be easily obtained by pointlight sources typified by an incandescent lamp and an LED or linearlight sources typified by a fluorescent lamp. Accordingly, thelight-emitting element is extremely effective for use as a surface lightsource applicable to lighting and the like.

Light-emitting elements utilizing electroluminescence are broadlyclassified according to whether they use an organic compound or aninorganic compound as a light-emitting substance. When an organiccompound is used as a light-emitting substance, by voltage applicationto a light-emitting element, electrons and holes are injected into alayer including the light-emitting organic compound from a pair ofelectrodes, whereby current flows. The carriers (electrons and holes)are recombined, and thus, the light-emitting organic compound isexcited. The light-emitting organic compound returns to a ground statefrom the excited state, thereby emitting light.

Because of such a mechanism, the light-emitting element is referred toas a current-excitation light-emitting element. Note that the excitedstate of an organic compound can be either a singlet excited state or atriplet excited state, and light emission from the singlet excited stateis referred to as fluorescence, and light emission from the tripletexcited state is referred to as phosphorescence.

In improving element characteristics of such a light-emitting element,there are a lot of problems which depend on a substance, and in order tosolve the problems, improvement of an element structure, development ofa substance, and the like have been carried out (for example, seeNon-Patent Document 1).

REFERENCE Non-Patent Document

-   [Non-Patent Document 1] Meng-Huan Ho, Yao-Shan Wu and Chin H. Chen,    2005 SID International Symposium Digest of Technical Papers,    Vol. XXXVI. pp. 802-805

SUMMARY OF THE INVENTION

Therefore, it is an object to provide a novel material having ahole-transporting property.

It is another object to provide a light-emitting element with high lightemission efficiency.

It is another object to reduce power consumption of a light-emittingelement, a light-emitting device, an electronic device, and a lightingdevice.

An aspect of the present invention is a carbazole derivative representedby the general formula (1).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; α and β independentlyrepresent a substituted or unsubstituted arylene group having 6 to 12carbon atoms which form a ring; R¹ represents an alkyl group having 1 to4 carbon atoms or a substituted or unsubstituted aryl group having 6 to10 carbon atoms which form a ring; and R¹¹ to R¹⁷ and R²¹ to R²⁸independently represent hydrogen, an alkyl group having 1 to 4 carbonatoms, or a substituted or unsubstituted aryl group having 6 to 10carbon atoms which form a ring. In the case where Ar¹ has a substituent,an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to10 carbon atoms which form a ring can be given as the substituent. Inthe case where R¹ has a substituent, an alkyl group having 1 to 4 carbonatoms or an aryl group having 6 to 10 carbon atoms which form a ring canbe given as the substituent. R¹¹ to R¹⁷ and R²¹ to R²⁸ may independentlyhave a substituent, and in that case, an alkyl group having 1 to 4carbon atoms or an aryl group having 6 to 10 carbon atoms which form aring can be given as the substituent.

Another aspect of the present invention is a carbazole derivativerepresented by the general formula (2).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; α and β independentlyrepresent a substituted or unsubstituted phenylene group; R¹ representsan alkyl group having 1 to 4 carbon atoms or a substituted orunsubstituted aryl group having 6 to 10 carbon atoms which form a ring;and R¹¹ to R¹⁷ and R²¹ to R²⁸ independently represent hydrogen, an alkylgroup having 1 to 4 carbon atoms, or a substituted or unsubstituted arylgroup having 6 to 10 carbon atoms which form a ring. In the case whereAr¹ has a substituent, an alkyl group having 1 to 4 carbon atoms or anaryl group having 6 to 10 carbon atoms which form a ring can be given asthe substituent. In the case where R¹ has a substituent, an alkyl grouphaving 1 to 4 carbon atoms or a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring can be given as thesubstituent. R¹¹ to R¹⁷ and R²¹ to R²⁸ may independently have asubstituent, and in that case, an alkyl group having 1 to 4 carbon atomsor an aryl group having 6 to 10 carbon atoms which form a ring can begiven as the substituent.

Another aspect of the present invention is a carbazole derivativerepresented by the general formula (3).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; R¹ represents an alkylgroup having 1 to 4 carbon atoms or a substituted or unsubstituted arylgroup having 6 to 10 carbon atoms which form a ring; R¹¹ to R¹⁷ and R²¹to R²⁸ independently represent hydrogen, an alkyl group having 1 to 4carbon atoms, or a substituted or unsubstituted aryl group having 6 to10 carbon atoms which form a ring; and R³¹ to R³⁴ and R⁴¹ to R⁴⁴independently represent hydrogen or an alkyl group having 1 to 4 carbonatoms. In the case where Ar¹ has a substituent, an alkyl group having 1to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms whichform a ring can be given as the substituent. In the case where R¹ has asubstituent, an alkyl group having 1 to 4 carbon atoms or an aryl grouphaving 6 to 10 carbon atoms which form a ring can be given as thesubstituent. R¹¹ to R¹⁷ and R²¹ to R²⁸ may independently have asubstituent, and in that case, an alkyl group having 1 to 4 carbon atomsor an aryl group having 6 to 10 carbon atoms which form a ring can begiven as the substituent.

Another aspect of the present invention is a carbazole derivativerepresented by the general formula (4).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; R¹ represents an alkylgroup having 1 to 4 carbon atoms or a substituted or unsubstituted arylgroup having 6 to 10 carbon atoms which form a ring; and R¹¹ to R¹⁷ andR²¹ to R²⁸ independently represent hydrogen, an alkyl group having 1 to4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to10 carbon atoms which form a ring. In the case where Ar¹ has asubstituent, an alkyl group having 1 to 4 carbon atoms or an aryl grouphaving 6 to 10 carbon atoms which form a ring can be given as thesubstituent. In the case where R¹ has a substituent, an alkyl grouphaving 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atomswhich form a ring can be given as the substituent. R¹¹ to R¹⁷ and R²¹ toR²⁸ may independently have a substituent, and in that case, an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbonatoms which form a ring can be given as the substituent.

Another aspect of the present invention is a carbazole derivativerepresented by the general formula (5).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; R¹¹ to R¹⁷ and R²¹ to R²⁸independently represent hydrogen, an alkyl group having 1 to 4 carbonatoms, or a substituted or unsubstituted aryl group having 6 to 10carbon atoms which form a ring; and R⁵¹ to R⁵⁵ independently representhydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl grouphaving 6 to 10 carbon atoms which form a ring. In the case where Ar¹ hasa substituent, an alkyl group having 1 to 4 carbon atoms or an arylgroup having 6 to 10 carbon atoms which form a ring can be given as thesubstituent. R¹¹ to R¹⁷ and R²¹ to R²⁸ may independently have asubstituent, and in that case, an alkyl group having 1 to 4 carbon atomsor an aryl group having 6 to 10 carbon atoms which form a ring can begiven as the substituent.

Another aspect of the present invention is a carbazole derivativerepresented by the general formula (6).

In the formula, R⁶¹ to R⁶⁵ independently represent hydrogen, an alkylgroup having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbonatoms which form a ring.

Another aspect of the present invention is a light-emitting elementusing any of the above carbazole derivatives. Specifically, thelight-emitting element includes any of the above carbazole derivativesbetween a pair of electrodes.

Another aspect of the present invention is a light-emitting elementincluding a light-emitting layer between a pair of electrodes, in whichthe light-emitting layer includes any of the above carbazolederivatives.

One embodiment of a light-emitting device of the present inventionincludes a light-emitting element in which a layer containing alight-emitting substance is included between a pair of electrodes andany of the above carbazole derivatives is included in the layercontaining a light-emitting substance, and also includes a means forcontrolling light emission of the light-emitting element. Note that thelight-emitting device in this specification includes an image displaydevice, a light-emitting device, and a light source (including alighting device). Further, the light-emitting device includes all of thefollowing modules: modules in which a connector such as a flexibleprinted circuit (FPC), a tape automated bonding (TAB) tape, or a tapecarrier package (TCP) is attached to a panel; modules having a TAB tapeor a TCP provided with a printed wiring board at the end thereof; andmodules having an integrated circuit (IC) directly mounted on alight-emitting element by a chip-on-glass (COG) method.

Further, an electronic device in which one embodiment of thelight-emitting element of the present invention is used for a displayportion is also included in the category of the present invention.Consequently, one embodiment of an electronic device of the presentinvention includes a display portion, in which the display portion isprovided with the above light-emitting element and a means forcontrolling light emission of the light-emitting element.

Furthermore, a lighting device using one embodiment of thelight-emitting device of the present invention is also included in thecategory of the present invention. Therefore, one embodiment of thelighting device of the present invention is provided with the abovelight-emitting device.

One embodiment of the carbazole derivative of the present invention is amaterial having a hole-transporting property.

One embodiment of the carbazole derivative of the present invention canbe used as a hole-transporting layer of a light-emitting element.

Further, one embodiment of the carbazole derivative of the presentinvention can be used either as a light-emitting material (including adopant material) or as a host material in a light-emitting layer of alight-emitting element.

In a light-emitting element using one embodiment of the carbazolederivative of the present invention, light emission from alight-emitting layer can be efficiently obtained.

Therefore, a light-emitting element, a light-emitting device, anelectronic device, and a lighting device with reduced power consumptioncan be provided by using one embodiment of the carbazole derivative ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are views each illustrating a light-emitting element.

FIG. 2 is a view illustrating a light-emitting element.

FIG. 3 is a view illustrating a light-emitting element.

FIGS. 4A and 4B are views illustrating a light-emitting device.

FIGS. 5A and 5B are views illustrating a light-emitting device.

FIGS. 6A to 6E are views each illustrating an electronic device.

FIG. 7 is a view illustrating an electronic device.

FIGS. 8A and 8B are views each illustrating a lighting device.

FIG. 9 is a view illustrating a lighting device.

FIG. 10 is a view illustrating a light-emitting element of Example 3.

FIGS. 11A and 11B are views each illustrating a light-emitting element.

FIGS. 12A and 12B are graphs showing a ¹H NMR chart of PCBACzP.

FIG. 13 is a graph showing an absorption spectrum of a toluene solutionof PCBACzP.

FIG. 14 is a graph showing an absorption spectrum of a thin film ofPCBACzP.

FIG. 15 is a graph showing an emission spectrum of the toluene solutionof PCBACzP.

FIG. 16 is a graph showing an emission spectrum of the thin film ofPCBACzP.

FIG. 17 is a graph showing CV measurement results of PCBACzP.

FIG. 18 is a graph showing CV measurement results of PCBACzP.

FIGS. 19A and 19B are graphs showing a ¹H NMR chart of PCBBiCP.

FIG. 20 is a graph showing an emission spectrum of a toluene solution ofPCBBiCP.

FIG. 21 is a graph showing an emission spectrum of a thin film ofPCBBiCP.

FIG. 22 is a graph showing an emission spectrum of the toluene solutionof PCBBiCP.

FIG. 23 is a graph showing an emission spectrum of the thin film ofPCBBiCP.

FIG. 24 is a graph showing CV measurement results of PCBBiCP.

FIG. 25 is a graph showing CV measurement results of PCBBiCP.

FIG. 26 is a graph showing the current density-luminance characteristicsof a comparative light-emitting element, a light-emitting element 1, anda light-emitting element 2.

FIG. 27 is a graph showing the voltage-luminance characteristics of thecomparative light-emitting element, the light-emitting element 1, andthe light-emitting element 2.

FIG. 28 is a graph showing the luminance-current efficiencycharacteristics of the comparative light-emitting element, thelight-emitting element 1, and the light-emitting element 2.

FIG. 29 is a graph showing emission spectra of the comparativelight-emitting element, the light-emitting element 1, and thelight-emitting element 2.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments and examples of the present invention will bedescribed with reference to the drawings. Note that the presentinvention is not limited to the following description, and it will beeasily understood by those skilled in the art that various changes andmodifications can be made without departing from the spirit and scope ofthe present invention. Therefore, the present invention should not beconstrued as being limited to the description in the followingembodiments and examples.

[Embodiment 1]

In this embodiment, one embodiment of a carbazole derivative of thepresent invention will be described.

A carbazole derivative according to this embodiment is represented bythe general formula (1).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; α and β independentlyrepresent a substituted or unsubstituted arylene group having 6 to 12carbon atoms which form a ring; R¹ represents an alkyl group having 1 to4 carbon atoms or a substituted or unsubstituted aryl group having 6 to10 carbon atoms which form a ring; and R¹¹ to R¹⁷ and R²¹ to R²⁸independently represent hydrogen, an alkyl group having 1 to 4 carbonatoms, or a substituted or unsubstituted aryl group having 6 to 10carbon atoms which form a ring. In the case where Ar¹ has a substituent,an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to10 carbon atoms which form a ring can be given as the substituent. Inthe case where R¹ has a substituent, an alkyl group having 1 to 4 carbonatoms or an aryl group having 6 to 10 carbon atoms which form a ring canbe given as the substituent. R¹¹ to R¹⁷ and R²¹ to R²⁸ may independentlyhave a substituent, and in that case, an alkyl group having 1 to 4carbon atoms or an aryl group having 6 to 10 carbon atoms which form aring can be given as the substituent.

A carbazole derivative according to this embodiment is represented bythe general formula (2).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; α and β independentlyrepresent a substituted or unsubstituted phenylene group; R¹ representsan alkyl group having 1 to 4 carbon atoms or a substituted orunsubstituted aryl group having 6 to 10 carbon atoms which form a ring;and R¹¹ to R¹⁷ and R²¹ to R²⁸ independently represent hydrogen, an alkylgroup having 1 to 4 carbon atoms, or a substituted or unsubstituted arylgroup having 6 to 10 carbon atoms which form a ring. In the case whereAr¹ has a substituent, an alkyl group having 1 to 4 carbon atoms or anaryl group having 6 to 10 carbon atoms which form a ring can be given asthe substituent. In the case where R¹ has a substituent, an alkyl grouphaving 1 to 4 carbon atoms or a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring can be given as thesubstituent. R¹¹ to R¹⁷ and R²¹ to R²⁸ may independently have asubstituent, and in that case, an alkyl group having 1 to 4 carbon atomsor an aryl group having 6 to 10 carbon atoms which form a ring can begiven as the substituent.

A carbazole derivative according to this embodiment is represented bythe general formula (3).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; R¹ represents an alkylgroup having 1 to 4 carbon atoms or a substituted or unsubstituted arylgroup having 6 to 10 carbon atoms which form a ring; R¹¹ to R¹⁷ and R²¹to R²⁸ independently represent hydrogen, an alkyl group having 1 to 4carbon atoms, or a substituted or unsubstituted aryl group having 6 to10 carbon atoms which form a ring; and R³¹ to R³⁴ and R⁴¹ to R⁴⁴independently represent hydrogen or an alkyl group having 1 to 4 carbonatoms. In the case where Ar¹ has a substituent, an alkyl group having 1to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms whichform a ring can be given as the substituent. In the case where R¹ has asubstituent, an alkyl group having 1 to 4 carbon atoms or an aryl grouphaving 6 to 10 carbon atoms which form a ring can be given as thesubstituent. R¹¹ to R¹⁷ and R²¹ to R²⁸ may independently have asubstituent, and in that case, an alkyl group having 1 to 4 carbon atomsor an aryl group having 6 to 10 carbon atoms which form a ring can begiven as the substituent.

A carbazole derivative according to this embodiment is represented bythe general formula (4).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; R¹ represents an alkylgroup having 1 to 4 carbon atoms or a substituted or unsubstituted arylgroup having 6 to 10 carbon atoms which form a ring; and R¹¹ to R¹⁷ andR²¹ to R²⁸ independently represent hydrogen, an alkyl group having 1 to4 carbon atoms, or a substituted or unsubstituted aryl group having 6 to10 carbon atoms which form a ring. In the case where Ar¹ has asubstituent, an alkyl group having 1 to 4 carbon atoms or an aryl grouphaving 6 to 10 carbon atoms which form a ring can be given as thesubstituent. In the case where R¹ has a substituent, an alkyl grouphaving 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atomswhich form a ring can be given as the substituent. R¹¹ to R¹⁷ and R²¹ toR²⁸ may independently have a substituent, and in that case, an alkylgroup having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbonatoms which form a ring can be given as the substituent.

A carbazole derivative according to this embodiment is represented bythe general formula (5).

In the formula, Ar¹ represents a substituted or unsubstituted aryl grouphaving 6 to 10 carbon atoms which form a ring; R¹¹ to R¹⁷ and R²¹ to R²⁸independently represent hydrogen, an alkyl group having 1 to 4 carbonatoms, or a substituted or unsubstituted aryl group having 6 to 10carbon atoms which form a ring; and R⁵¹ to R⁵⁵ independently representhydrogen, an alkyl group having 1 to 4 carbon atoms, or an aryl grouphaving 6 to 10 carbon atoms which form a ring. In the case where Ar¹ hasa substituent, an alkyl group having 1 to 4 carbon atoms or an arylgroup having 6 to 10 carbon atoms which form a ring can be given as thesubstituent. R¹¹ to R¹⁷ and R²¹ to R²⁸ may independently have asubstituent, and in that case, an alkyl group having 1 to 4 carbon atomsor an aryl group having 6 to 10 carbon atoms which form a ring can begiven as the substituent.

A carbazole derivative according to this embodiment is represented bythe general formula (6).

In the formula, R⁶¹ to R⁶⁵ independently represent hydrogen, an alkylgroup having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbonatoms which form a ring.

Note that the number of carbon atoms of the aryl group or the arylenegroup described in this specification represents the number of carbonatoms which form a ring of the main skeleton, and do not include thenumber of carbon atoms of a substituent bonded to the carbon atoms whichform the ring of the main skeleton of the aryl group or the arylenegroup. An alkyl group having 1 to 4 carbon atoms or an aryl group having6 to 10 carbon atoms can be given as the substituent bonded to the arylgroup. Specifically, a methyl group, an ethyl group, a propyl group, abutyl group, a phenyl group, a naphthyl group, or the like can be given.An alkyl group having 1 to 4 carbon atoms can be given as thesubstituent bonded to the arylene group. Specifically, a methyl group,an ethyl group, a propyl group, a butyl group, or the like can be used.Note that the aryl group or the arylene group may have one substituentor more substituents.

In the general formulae (1) to (5), as specific examples of groupsrepresented by Ar¹, substituents represented by the structural formulae(11-1) to (11-21) can be given, for example.

As specific examples of groups represented by α and β, substituentsrepresented by the structural formulae (12-1) to (12-21) can be given,for example.

As specific examples of groups represented by R¹, substituentsrepresented by the structural formulae (13-1) to (13-29) can be given,for example.

As specific examples of groups represented by R¹¹ to R¹⁷ and R²¹ to R²⁸,substituents represented by the structural formulae (14-1) to (14-30)can be given, for example.

As specific examples of groups represented by R⁵¹ to R⁵⁵, substituentsrepresented by the structural formulae (15-1) to (15-22) can be given,for example.

As specific examples of the carbazole derivatives represented by thegeneral formulae (1) to (6), carbazole derivatives represented by thestructural formulae (100) to (178) can be given, for example. However,the present invention is not limited thereto.

As a synthesis method of a carbazole derivative of the presentinvention, various reactions can be applied. For example, a carbazolederivative of the present invention can be synthesized by conducting asynthesis reaction shown in the following reaction formula (Z-1).

An organic compound (Compound C) represented by the general formula (1)shown in this embodiment can be obtained in such a manner that an aminecompound including carbazole (Compound A) and a halide carbazolederivative (Compound B) are coupled in the presence of a base through aHartwig-Buchwald reaction using a palladium catalyst or through anUllmann reaction using copper or a copper compound (the reaction formula(Z-1)).

In the reaction formula (Z-1), X¹ represents a halogen, preferablyiodine or bromine.

In the case where the Hartwig-Buchwald reaction is carried out in thereaction formula (Z-1), bis(dibenzylideneacetone)palladium(0),palladium(II) acetate, or the like can be used as the palladiumcatalyst. Examples of ligands of the palladium catalysts that can beused in the reaction formula (Z-1) are tri(tert-butyl)phosphine,tri(n-hexyl)phosphine, tricyclohexylphosphine, and the like. Examples ofbases that can be used in the reaction formula (Z-1) are organic basessuch as sodium tert-butoxide, inorganic bases such as potassiumcarbonate, and the like. The solvents that can be used in the reactionformula (Z-1) are toluene, xylene, benzene, tetrahydrofuran, and thelike.

The case of performing the Ullmann reaction in the reaction formula(Z-1) is described. In the reaction formula (Z-1), copper(I) iodide,copper(II) acetate, or the like can be used as the copper compound.Further, copper can be used other than the copper compound. As a basethat can be used in the reaction formula (Z-1), inorganic bases such aspotassium carbonate are given. Examples of solvents that can be used inthe reaction formula (Z-1) are1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (DMPU), toluene,xylene, benzene, and the like. In the Ullmann reaction, the desiredsubstance can be obtained in a shorter time and in a higher yield whenthe reaction temperature is 100° C. or higher; therefore, it ispreferable to use DMPU or xylene that has a high boiling point. Becausethe reaction temperature is further preferably 150° C. or higher, DMPUis more preferably used.

In the above manner, the carbazole derivative of this embodiment can besynthesized.

The carbazole derivative of this embodiment is a material having ahole-transporting property.

One embodiment of the carbazole derivative of the present invention canbe used as a hole-transporting material for a functional layer of alight-emitting element. For example, one embodiment of the carbazolederivative of the present invention can be used for a hole-transportinglayer or a hole-injecting layer.

The carbazole derivative of this embodiment can be used alone as a lightemission center material in a layer containing a light-emittingsubstance (a light-emitting layer). Alternatively, the carbazolederivative of this embodiment can also be used as a host material. Lightemission from a dopant material functioning as a light-emittingsubstance can be obtained with a structure in which the dopant materialfunctioning as a light-emitting substance is dispersed in the carbazolederivative of this embodiment. When the carbazole derivative of thisembodiment is used as a host material, light emission from a dopantmaterial can be efficiently obtained.

Further, a layer in which the carbazole derivative of this embodiment isdispersed in a (host) material having a larger band gap than thecarbazole derivative of this embodiment can be used as a layercontaining a light-emitting substance. In that case, light emission fromthe carbazole derivative of this embodiment can be obtained. That is,the carbazole derivative of this embodiment can also function as adopant material.

[Embodiment 2]

One embodiment of a light-emitting element using a carbazole derivativeof the present invention will be described with reference to FIG. 1A.

In one embodiment of the light-emitting element of the presentinvention, an EL layer including at least a layer containing alight-emitting substance (the layer is also referred to as alight-emitting layer) is provided between a pair of electrodes. The ELlayer may also include a plurality of layers in addition to the layercontaining a light-emitting substance. The plurality of layers are acombination of layers formed from a substance having a highcarrier-injecting property and a substance having a highcarrier-transporting property. Those layers are stacked so that alight-emitting region is formed in a region away from the electrodes,that is, carriers are recombined in a region away from the electrodes.In this specification, the layer formed from a substance having a highcarrier-injecting property or a substance having a highcarrier-transporting property is also referred to as a functional layerfunctioning to inject or transport carriers or the like. For thefunctional layer, it is possible to use a layer containing a substancehaving a high hole-injecting property (also referred to as ahole-injecting layer), a layer containing a substance having a highhole-transporting property (also referred to as a hole-transportinglayer), a layer containing a substance having a high electron-injectingproperty (also referred to as an electron-injecting layer), a layercontaining a substance having a high electron-transporting property(also referred to as an electron-transporting layer), and the like.

In a light-emitting element of this embodiment illustrated in each ofFIGS. 1A to 1C, an EL layer 108 is provided between a pair ofelectrodes: a first electrode 102 and a second electrode 107. The ELlayer 108 has a first layer 103, a second layer 104, a third layer 105,and a fourth layer 106. The light-emitting element in each of FIGS. 1Ato 1C includes the first electrode 102 over a substrate 101; the firstlayer 103, the second layer 104, the third layer 105, and the fourthlayer 106 stacked in this order over the first electrode 102; and thesecond electrode 107 provided thereover. Note that in this embodiment,the following description will be made on the assumption that the firstelectrode 102 functions as an anode and that the second electrode 107functions as a cathode.

The substrate 101 is used as a support of the light-emitting element.For the substrate 101, glass, quartz, plastic, or the like can be used,for example. Alternatively, a flexible substrate may be used. A flexiblesubstrate is a substrate that can be bent, such as a plastic substratemade of polycarbonate, polyarylate, or polyether sulfone, for example.Alternatively, a film (made of polypropylene, polyester, vinyl,polyvinyl fluoride, vinyl chloride, or the like), an inorganic filmformed by evaporation, or the like can be used. Note that othersubstrates may also be used as long as they function as a support in amanufacturing process of the light-emitting element.

The first electrode 102 is preferably formed using a metal, an alloy, aconductive compound, a mixture of these, or the like each having a highwork function (specifically, a work function of 4.0 eV or higher).Specifically, for example, indium tin oxide (ITO), indium tin oxidecontaining silicon or silicon oxide, indium zinc oxide (IZO), indiumoxide containing tungsten oxide and zinc oxide (IWZO), and the like aregiven. Films of those conductive metal oxides are generally formed bysputtering, but they may be formed by a sol-gel method or the like. Forexample, a film of indium zinc oxide (IZO) can be formed by a sputteringmethod using a target in which zinc oxide is added to indium oxide at 1wt % to 20 wt %. A film of indium oxide containing tungsten oxide andzinc oxide (IWZO) can be formed by a sputtering method using a target inwhich tungsten oxide and zinc oxide are added to indium oxide at 0.5 wt% to 5 wt % and 0.1 wt % to 1 wt %, respectively. In addition, gold(Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr),molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), anitride of a metal material (such as titanium nitride), or the like canbe used.

The first layer 103 contains a substance having a high hole-injectingproperty. Molybdenum oxide, vanadium oxide, ruthenium oxide, tungstenoxide, manganese oxide, or the like can be used. Alternatively, thefirst layer 103 can be formed using any of the following materials:phthalocyanine-based compounds such as phthalocyanine (abbreviation:H₂Pc) and copper phthalocyanine (abbreviation: CuPc); aromatic aminecompounds such as4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation:DPAB) andN,N′-bis[4-[bis(3-methylphenyl)amino]phenyl]-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: DNTPD); high molecular compounds such aspoly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS);and the like.

Further, the first layer 103 can be formed from a composite materialformed by a composition of an organic compound and an inorganiccompound. In particular, a composite material which contains an organiccompound and an inorganic compound showing an electron-acceptingproperty to the organic compound is excellent in a hole-injectingproperty and a hole-transporting property since electrons aretransferred between the organic compound and the inorganic compound andcarrier density is increased.

In the case where the first layer 103 is formed using a compositematerial formed by a composition of an organic compound and an inorganiccompound, ohmic contact with the first electrode 102 becomes possible,and the material for the first electrode can be selected regardless ofits work function.

As the inorganic compound used for the composite material, an oxide of atransition metal is preferably used. In addition, an oxide of metalsthat belong to Group 4 to Group 8 of the periodic table can be given.Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromiumoxide, molybdenum oxide, tungsten oxide, manganese oxide, and rheniumoxide are preferable because of their high electron-acceptingproperties. Among them, molybdenum oxide is especially preferablebecause it is stable in the air, has a low hygroscopic property, and iseasily handled.

As the organic compound used for the composite material, variouscompounds such as an aromatic amine compound, a carbazole derivative,aromatic hydrocarbon, and a high molecular compound (such as oligomer,dendrimer, or polymer) can be used. Note that the organic compound usedfor the composite material is preferably an organic compound having ahigh hole-transporting property. Specifically, a substance having a holemobility of 10⁻⁶ cm²/Vs or higher is preferable. As the organic compoundthat can be used for the composite material, one embodiment of thecarbazole derivative of the present invention can be used. The organiccompounds that can be used for the composite material is specificallygiven below.

As aromatic amine compounds, for example,N,N′-di(p-tolyl)-N,N′-diphenyl-p-phenylenediamine (abbreviation:DTDPPA), 4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl(abbreviation: DPAB),N,N′-bis[4-[bis(3-methylphenyl)amino]phenyl]-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: DNTPD),1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B), and the like can be given.

As carbazole derivatives that can be used for the composite material,for example,3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1),3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2),3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1), and the like can be given.

As other examples of carbazole derivatives that can be used for thecomposite material, for example, 4,4′-di(N-carbazolyl)biphenyl(abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene(abbreviation: TCPB), 9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene(abbreviation: CzPA),1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, and the likecan be given.

As aromatic hydrocarbon that can be used for the composite material, forexample, 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation:t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene,9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA),2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA),9,10-di(2-naphthyl)anthracene (abbreviation: DNA),9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene(abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene(abbreviation: DMNA),2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene,9,10-bis[2-(1-naphthyl)phenyl]anthracene,2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene,2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9′-bianthryl,10,10′-diphenyl-9,9′-bianthryl,10,10′-bis(2-phenylphenyl)-9,9′-bianthryl,10,10′-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9′-bianthryl, anthracene,tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, andthe like can be given. Alternatively, pentacene, coronene, or the likecan also be used. As described above, aromatic hydrocarbon having a holemobility of 1×10⁻⁶ cm²/Vs or higher and 14 to 42 carbon atoms is morepreferable.

The aromatic hydrocarbon that can be used for the composite material mayhave a vinyl skeleton. As the aromatic hydrocarbon having a vinyl group,for example, 4,4′-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi),9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA),and the like can be given.

Moreover, a high molecular compound such as poly(N-vinylcarbazole)(abbreviation: PVK) or poly(4-vinyltriphenylamine) (abbreviation: PVTPA)can also be used.

The second layer 104 can be formed using a substance having a highhole-transporting property. In this embodiment, the second layer 104 canbe formed using the carbazole derivative of the present invention whichis described in Embodiment 1. Note that the second layer 104 is notlimited to a single layer, and may be a mixed layer or a stack of two ormore layers including a substance which has a higher hole-transportingproperty than an electron-transporting property and whose hole mobilityis mainly 10⁻⁶ cm²/Vs or higher.

The second layer 104 is preferably formed using a substance having ahigh hole-transporting property, specifically, an aromatic aminecompound (that is, a compound having a benzene ring-nitrogen bond). Asexamples of materials which are widely used,4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl, a derivative thereofsuch as 4,4′-bis[N-(1-napthyl)-N-phenylamino]biphenyl (hereinafterreferred to as NPB), a starburst aromatic amine compound such as4,4′,4″-tris(N,N-diphenyl-amino)triphenylamine,4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine, and thelike can be given. Most of the substances mentioned here have a holemobility of 10⁻⁶ cm²/Vs or higher. Note that the second layer 104 is notlimited to a single layer, and may be a mixed layer or a stack of two ormore layers including the aforementioned substances.

Alternatively, a material having a hole-transporting property may beadded to a high molecular compound that is electrically inactive, suchas PMMA.

Further alternatively, a high molecular compound such aspoly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine)(abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylamide](abbreviation: PTPDMA), orpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine (abbreviation:Poly-TPD) may be used, and further, the material having ahole-transporting property may be added to the above high molecularcompound, as appropriate.

The third layer 105 contains a light-emitting substance (the layer isalso referred to as a light-emitting layer). A carbazole derivative ofthe present invention exhibits blue light emission, and thus can be usedas a light-emitting substance in a light-emitting element.

Alternatively, in the third layer 105, a carbazole derivative of thepresent invention can also be used as a host material. Light emissionfrom a dopant material functioning as a light-emitting substance can beobtained with a structure in which the dopant material functioning as alight-emitting substance is dispersed in a carbazole derivative of thepresent invention.

A carbazole derivative of the present invention is a material having ahole-transporting property.

When a carbazole derivative of the present invention is used as amaterial in which another light-emitting substance is dispersed, anemission color originating from the light-emitting substance can beobtained. Further, it is possible to obtain a mixed color of an emissioncolor originating from the carbazole derivative of the present inventionand an emission color originating from the light-emitting substancewhich is dispersed in the carbazole derivative.

Further, a layer in which a carbazole derivative of the presentinvention is dispersed in a (host) material having a larger band gapthan the carbazole derivative of the present invention can be used as alayer containing a light-emitting substance; thus, light emission fromthe carbazole derivative of the present invention can be obtained. Thatis, a carbazole derivative of the present invention also functions as adopant material. In this case, a light-emitting element that can exhibitblue light emission can be manufactured by utilizing light emission ofthe carbazole derivative of the present invention.

Here, any of a variety of materials can be used as a light-emittingsubstance that is to be dispersed in a carbazole derivative of thepresent invention. Specifically, a fluorescent substance that emitsfluorescence can be used, for example:N,N″-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N′,N′-triphenyl-1,4-phenylenediamine](abbreviation: DPABPA),N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: 2PCAPPA),N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPPA),N,N,N′,N′,N″,N″,N′″,N′″-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine(abbreviation: DBC1), coumarin 30,N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCABPhA),N-(9,10-diphenyl-2-anthryl)-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPA),N-[9,10-bis(1,1′-biphenyl-2-yl)-2-anthryl]-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPABPhA),9,10-bis(1,1′-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine(abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine(abbreviation: DPhAPhA), coumarin 545T, N,N′-diphenylquinacridone(abbreviation: DPQd), rubrene,5,12-bis(1,1′-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT),2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile(abbreviation: DCM1),2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCM2),N,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation:p-mPhTD),7,14-diphenyl-N,N,N′,N′-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine(abbreviation: p-mPhAFD),2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCJTI),2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: DCJTB),2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile(abbreviation: BisDCM),2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile(abbreviation: BisDCJTM), or the like.

Alternatively, a phosphorescent substance that emits phosphorescence canbe used, for example: bis(benzo[h]quinolinato)iridium(III)acetylacetonate (abbreviation: Ir(bzq)₂(acac)),bis(2,4-diphenyl-1,3-oxazolato-N,C²′)iridium(III) acetylacetonate(abbreviation: Ir(dpo)₂(acac)),bis[2-(4′-perfluorophenylphenyl)pyridinato]iridium(III) acetylacetonate(abbreviation: Ir(p-PF-ph)₂(acac)),bis(2-phenylbenzothiazolato-N,C²′)iridium(III) acetylacetonate(abbreviation: Ir(bt)₂(acac)),bis[2-(2′-benzo[4,5-a]thienyl)pyridinato-N,C³′]iridium(III)acetylacetonate (abbreviation: Ir(btp)₂(acac)),bis(1-phenylisoquinolinato-N,C²′)iridium(III) acetylacetonate(abbreviation: Ir(piq)₂(acac)),(acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III)(abbreviation: Ir(Fdpq)₂(acac)),(acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: Ir(tppr)₂(acac)),2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II)(abbreviation: PtOEP),tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III)(abbreviation: Eu(DBM)₃(Phen)),tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III)(abbreviation: Eu(TTA)₃(Phen)), or the like.

The fourth layer 106 can be formed using a substance having a highelectron-transporting property. For example, the fourth layer 106 isformed using a metal complex having a quinoline skeleton or abenzoquinoline skeleton, such as tris(8-quinolinolato)aluminum(abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(abbreviation: Almq₃), bis(10-hydroxybenzo[h]quinolinato)beryllium(abbreviation: BeBq₂), orbis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (abbreviation:BAlq). Other examples that can be used are metal complexes having anoxazole-based ligand or a thiazole-based ligand, such asbis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)₂) andbis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ)₂).Furthermore, as an alternative to metal complexes, the following canalso be used: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole(abbreviation: PBD),1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7),3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole(abbreviation: TAZ), bathophenanthroline (abbreviation: Bphen),bathocuproine (abbreviation: BCP), and the like. Most of the substancesmentioned here have an electron mobility of 10⁻⁶ cm²/Vs or higher.Further, the electron-transporting layer is not limited to a singlelayer, and may be a stack of two or more layers each containing any ofthe above substances.

Further, a layer having a function of promoting electron injection (anelectron-injecting layer) may be provided between the fourth layer 106and the second electrode 107. For the layer having a function ofpromoting electron injection, an alkali metal, an alkaline earth metal,or a compound thereof, such as lithium fluoride (LiF), cesium fluoride(CsF), or calcium fluoride (CaF₂) can be used.

Further, a composite material formed by a composition of an organiccompound and an inorganic compound can be used for the layer having afunction of promoting electron injection. For example, a layer of asubstance having an electron-transporting property which furtherincludes an alkali metal, an alkaline earth metal, or a compoundthereof, such as a layer of Alq which further includes magnesium (Mg)can be used. Note that as the electron-injecting layer, it is preferableto use the layer formed of a substance having an electron-transportingproperty which further includes an alkali metal or an alkaline earthmetal because electrons can be efficiently injected from the secondelectrode 107.

As a substance for forming the second electrode 107, a metal, an alloy,an electrically conductive compound, a mixture thereof, or the like eachhaving a low work function (specifically, 3.8 eV or lower) can be used.As specific examples of such a cathode material, an element belonging toGroup 1 or Group 2 of the periodic table, that is, an alkali metal suchas lithium (Li) or cesium (Cs); an alkaline-earth metal such asmagnesium (Mg), calcium (Ca), or strontium (Sr); an alloy containing theelement belonging to Group 1 or Group 2 (MgAg, AlLi); a rare-earth metalsuch as europium (Eu) or ytterbium (Yb); an alloy thereof; and the likecan be given. However, when a layer having a function of promotingelectron injection is provided between the second electrode 107 and thefourth layer 106 so as to be stacked with the second electrode, variousconductive materials such as Al, Ag, ITO, or ITO containing silicon orsilicon oxide can be used for the second electrode 107 regardless of thework function.

A carbazole derivative of the present invention can also be used for afunctional layer of a light-emitting element.

Further, for the formation of the first layer 103, the second layer 104,the third layer 105, and the fourth layer 106, any of a variety ofmethods such as an evaporation method, a sputtering method, a dropletdischarging method (an inkjet method), a spin coating method, or aprinting method can be employed. A different formation method may beemployed for each electrode or each layer.

When a wet process is employed to form a thin film using a liquidcomposition which is obtained by dissolving a carbazole derivative ofthe present invention in a solvent, the thin film is formed in such amanner that a material for forming the thin film which includes thecarbazole derivative of the present invention is dissolved in thesolvent, the liquid composition is attached to a region where the thinfilm is to be formed, the solvent is removed, and the resulting materialis solidified.

For the wet process, any of the following methods can be employed: aspin coating method, a roll coating method, a spray method, a castingmethod, a dipping method, a droplet discharging (ejection) method (aninkjet method), a dispenser method, a variety of printing methods (amethod by which a thin film can be formed in a desired pattern, such asscreen (stencil) printing, offset (planographic) printing, letterpressprinting, or gravure (intaglio) printing, or the like. Note that withoutlimitation to the above methods, the compositions of the presentinvention can be used as long as a method in which a liquid compositionis used is employed.

In the above composition, a variety of solvents can be used. Forexample, the carbazole derivative can be dissolved in a solvent that hasan aromatic ring (e.g., a benzene ring), such as toluene, xylene,methoxybenzene (anisole), dodecylbenzene, or a mixed solvent ofdodecylbenzene and tetralin. Further, the above carbazole derivative canalso be dissolved in an organic solvent which does not include anaromatic ring, such as dimethylsulfoxide (DMSO), dimethylformamide(DMF), or chloroform.

As other examples of the solvents, there are ketone-based solvents suchas acetone, methyl ethyl ketone, diethyl ketone, n-propyl methyl ketone,and cyclohexanone; ester-based solvents such as ethyl acetate, n-propylacetate, n-butyl acetate, ethyl propionate, γ-butyrolactone, and diethylcarbonate; ether-based solvents such as diethyl ether, tetrahydrofuran,and dioxane; alcohol-based solvents such as ethanol, isopropanol,2-methoxyethanol, and 2-ethoxyethanol; and the like.

Further, a composition which is described in this embodiment may alsocontain another organic material. As the organic material, an aromaticcompound or a heteroaromatic compound which is solid at room temperaturecan be given. For the organic material, a low molecular compound or ahigh molecular compound can be used. When a low molecular compound isused, a low molecular compound (which may be referred to as a mediummolecular compound) including a substituent that can increase thesolubility in a solvent is preferably used.

The composition may further include a binder in order to improve thequality of a film which is formed. A high molecular compound that iselectrically inactive is preferably used as the binder. Specifically,polymethylmethacrylate (abbreviation: PMMA), polyimide, or the like canbe used.

In the light-emitting element of this embodiment which has the structureas described above, the potential difference between the first electrode102 and the second electrode 107 makes current flow, whereby holes andelectrons recombine in the third layer 105 containing a substance havinga high light-emitting property and thus light is emitted. That is, alight-emitting region is formed in the third layer 105.

Emitted light is extracted to the outside through one or both of thefirst electrode 102 and the second electrode 107. Accordingly, one orboth of the first electrode 102 and the second electrode 107 is/areformed using a substance having a light-transmitting property. When onlythe first electrode 102 is formed using a substance having alight-transmitting property, emitted light is extracted from thesubstrate side through the first electrode 102, as illustrated in FIG.1A. In contrast, when only the second electrode 107 is formed using asubstance having a light-transmitting property, emitted light isextracted from the side opposite to the substrate through the secondelectrode 107, as illustrated in FIG. 1B. When both the first electrode102 and the second electrode 107 are formed using a substance having alight-transmitting property, emitted light is extracted from both thesubstrate side and the side opposite to the substrate through the firstelectrode 102 and the second electrode 107, as illustrated in FIG. 1C.

Note that the structure of the layers provided between the firstelectrode 102 and the second electrode 107 is not limited to the above.A structure other than the above may alternatively be employed as longas a light-emitting region in which holes and electrons are recombinedis provided in a portion away from the first electrode 102 and thesecond electrode 107 in order to prevent quenching due to proximity ofthe light-emitting region to a metal.

In other words, there is no particular limitation on the stack structureof the layers as long as the hole-transporting layer or thelight-emitting layer which contains a carbazole derivative of thepresent invention is freely combined with the layer containing asubstance having a high electron-transporting property, the layercontaining a substance having a high hole-transporting property, thelayer containing a substance having a high electron-injecting property,the layer containing a substance having a high hole-injecting property,the layer containing a bipolar substance (a substance having a highelectron-transporting and a high hole-transporting property), the layercontaining a hole-blocking material, and the like.

In a light-emitting element illustrated in FIG. 2, over a substrate 301,an EL layer 308 is provided between a pair of electrodes: a firstelectrode 302 and a second electrode 307. The EL layer 308 includes afirst layer 303 formed from a substance having a highelectron-transporting property, a second layer 304 containing alight-emitting substance, a third layer 305 formed from a substancehaving a high hole-transporting property, and a fourth layer 306 formedfrom a substance having a high hole-injecting property. The firstelectrode 302 which functions as a cathode, the first layer 303 formedfrom a substance having a high electron-transporting property, thesecond layer 304 containing a light-emitting substance, the third layer305 formed from a substance having a high hole-transporting property,the fourth layer 306 formed from a substance having a highhole-injecting property, and the second electrode 307 which functions asan anode are stacked in that order.

A specific method for forming a light-emitting element is describedbelow.

In a light-emitting element of the present invention, an EL layer isinterposed between a pair of electrodes. The EL layer includes at leasta layer containing a light-emitting substance (the layer is alsoreferred to as a light-emitting layer). Furthermore, in addition to thelayer containing a light-emitting substance, the EL layer may includeanother functional layer (e.g., a hole-injecting layer, anelectron-transporting layer, and/or an electron-injecting layer). Theelectrodes (the first electrode and the second electrode), the layercontaining a light-emitting substance, and the functional layer may beformed by a wet process such as a droplet discharge method (an inkjetmethod), a spin coating method, or a printing method, or by a dryprocess such as a vacuum evaporation method, a CVD method, or asputtering method. The use of a wet process enables the formation atatmospheric pressure using a simple apparatus and process, and thusadvantageous effects of simplifying the process and improving theproductivity can be obtained. In contrast, in a dry process, dissolutionof a material is not needed, and thus, a material that has lowsolubility in a solution can be used, which leads to expansion ofmaterial choices.

All the thin films included in the light-emitting element may be formedby a wet process. In this case, the light-emitting element can bemanufactured with only facilities needed for a wet process.Alternatively, formation of the stacked layers up to formation of thelayer containing a light-emitting substance may be performed by a wetprocess whereas the functional layer, the second electrode, and the likewhich are stacked over the layer containing a light-emitting substancemay be formed by a dry process. Further alternatively, the firstelectrode and the functional layer may be formed by a dry process beforethe formation of the layer containing a light-emitting substance whereasthe layer containing a light-emitting substance, the functional layerstacked thereover, and the second electrode may be formed by a wetprocess. It is needless to say that the present invention is not limitedthereto. The light-emitting element can be formed by appropriateselection from a wet process and a dry process depending on a materialthat is to be used, a required film thickness, and an interface state.

In this embodiment, the light-emitting element is manufactured over asubstrate made of glass, plastic, or the like. When a plurality of suchlight-emitting elements are manufactured over one substrate, a passivematrix light-emitting device can be manufactured. Alternatively, forexample, thin film transistors (TFTs) are formed over a substrate madeof glass, plastic, or the like, and then, light-emitting elements may bemanufactured over an electrode that is electrically connected to theTFTs. Thus, an active matrix light-emitting device in which drive of thelight-emitting elements is controlled by the TFTs can be manufactured.Note that there is no particular limitation on the structure of the TFT.Either a staggered TFT or an inverted staggered TFT may be employed.Further, there is no particular limitation on the crystallinity of asemiconductor used for forming the TFTs, and an amorphous semiconductoror a crystalline semiconductor may be used. In addition, a drivercircuit formed over a TFT substrate may be formed using n-channel andp-channel TFTs, or using either n-channel or p-channel TFTs.

One embodiment of the carbazole derivative of the present invention is amaterial having a hole-transporting property.

One embodiment of the carbazole derivative of the present invention canbe used for a hole-transporting layer.

In addition, one embodiment of the carbazole derivative of the presentinvention can be used either as a light-emitting material (including adopant material) or as a host material in a light-emitting layer of alight-emitting element.

Light emission can be efficiently obtained from a light-emitting elementin which one embodiment of the carbazole derivative of the presentinvention is used as a hole-transporting layer.

Therefore, a light-emitting element, a light-emitting device, and anelectronic device with reduced power consumption can be provided byusing one embodiment of the carbazole derivative of the presentinvention.

[Embodiment 3]

In this embodiment, a light-emitting element having a differentstructure from the structure described in Embodiment 2 will be describedwith reference to FIGS. 11A and 11B.

A layer which controls movement of electron carriers may be providedbetween an electron-transporting layer and a light-emitting layer. FIG.11A illustrates a structure in which a layer 130 which controls movementof electron carriers is provided between a fourth layer 106 whichfunctions as an electron-transporting layer and a third layer 105 whichfunctions as a light-emitting layer (the third layer 105 is alsoreferred to as a light-emitting layer 105). The layer 130 which controlsmovement of electron carriers is a layer which is formed by adding asmall amount of substance having a high electron-trapping property tothe above material having a high electron-transporting property, or alayer formed by adding a material having a hole-transporting propertywith a low lowest unoccupied molecular orbital (LUMO) energy level to amaterial having a high electron-trapping property. With such a layer,movement of electron carriers is controlled, whereby carrier balance canbe adjusted. Such a structure is very effective in suppressing a problem(such as shortening of element lifetime) caused when electrons passthrough the third layer 105.

Further, another structure may be employed in which the light-emittinglayer 105 includes two or more layers. FIG. 11B illustrates an examplein which the light-emitting layer 105 includes two layers: a firstlight-emitting layer 105 a and a second light-emitting layer 105 b.

If the first light-emitting layer 105 a and the second light-emittinglayer 105 b are stacked in that order over the second layer 104 whichfunctions as a hole-transporting layer to form the light-emitting layer105, for example, a substance having a hole-transporting property can beused as a host material of the first light-emitting layer 105 a and asubstance having an electron-transporting property can be used for thesecond light-emitting layer 105 b.

A carbazole derivative of the present invention can be used alone for alight-emitting layer. Further, a carbazole derivative of the presentinvention can also be used either as a host material or as a dopantmaterial.

If a carbazole derivative of the present invention is used as a hostmaterial, light emission from a dopant material that functions as alight-emitting substance can be obtained with a structure in which thedopant material that functions as a light-emitting substance isdispersed in the carbazole derivative of the present invention.

On the other hand, when a carbazole derivative of the present inventionis used as a dopant material, light emission from the carbazolederivative of the present invention can be obtained with a structure inwhich the carbazole derivative of the present invention is added to alayer formed from a (host) material which has a larger band gap than thecarbazole derivative of the present invention.

A carbazole derivative of the present invention can be used for thefirst light-emitting layer 105 a and the second light-emitting layer 105b, and can be used as a dopant material of each layer. In the case wherea carbazole derivative of the present invention is used alone as alight-emitting layer or used as a host material, the carbazolederivative of the present invention can be used for the firstlight-emitting layer 105 a having a hole-transporting property.

Note that this embodiment can be combined as appropriate with anotherembodiment.

[Embodiment 4]

In this embodiment, one mode of a light-emitting element having astructure in which a plurality of light-emitting units according to thepresent invention are stacked (hereinafter this type of light-emittingelement is referred to as a stacked element) will be described withreference to FIG. 3. This light-emitting element has a plurality oflight-emitting units between a first electrode and a second electrode.

In FIG. 3, a first light-emitting unit 511 and a second light-emittingunit 512 are stacked between a first electrode 501 and a secondelectrode 502. In the formation of each the first electrode 501 and thesecond electrode 502, electrodes similar to those described inEmbodiment 2 can be used. The structures of the first light-emittingunit 511 and the second light-emitting unit 512 may be the same ordifferent. Their structures can be similar to that described inEmbodiment 2.

A charge generation layer 513 contains a composite material of anorganic compound and a metal oxide. This composite material of anorganic compound and a metal oxide is a composite material described inEmbodiment 2 and includes an organic compound and a metal oxide such asV₂O₅, MoO₃ or WO₃. As the organic compound, various compounds such as anaromatic amine compound, a carbazole derivative, aromatic hydrocarbon,and a high molecular compound (oligomer, dendrimer, polymer, or thelike) can be given. An organic compound having a hole mobility of 10⁻⁶cm²/Vs or higher is preferably used as a hole-transporting organiccompound. Note that any organic compound other than the above substancemay also be used as long as its hole-transporting property is higherthan its electron-transporting property. The composite material of anorganic compound and a metal oxide is excellent in a carrier-injectingproperty and a carrier-transporting property; therefore, low-voltagedriving and low-current driving can be achieved.

Note that the charge generation layer 513 may be formed by a combinationof a composite material of an organic compound and a metal oxide andanother material. For example, a layer containing the composite materialof an organic compound and a metal oxide may be used in combination witha layer containing a compound selected from an electron-donatingsubstance and a compound having a high electron-transporting property.Further, a layer containing the composite material of an organiccompound and a metal oxide may be used in combination with a transparentconductive film.

In any case, any layer can be employed as the charge generation layer513 provided between the first light-emitting unit 511 and the secondlight-emitting unit 512 as long as the layer injects electrons into oneof these light-emitting units and holes into the other when voltage isapplied to the first electrode 501 and the second electrode 502.

Although the light-emitting element having two light-emitting units isdescribed in this embodiment, a light-emitting element in which three ormore light-emitting units are stacked can be employed in a similar way.When the charge generation layer is provided between the pair ofelectrodes so as to partition the plural light-emitting units like inthe light-emitting element of this embodiment, light emission from ahigh luminance region can be achieved while the current density is keptlow. Accordingly, an element with a long lifetime can be realized.Further, in the case where the light-emitting element is applied to alighting device, voltage drop due to resistance of an electrode materialcan be reduced. Accordingly, light can be uniformly emitted from a largearea. Moreover, a light-emitting device of low power consumption thatcan be driven at low voltage can be achieved.

Note that this embodiment can be combined as appropriate with anotherembodiment.

[Embodiment 5]

In this embodiment, a light-emitting device manufactured using oneembodiment of the carbazole derivative of the present invention will bedescribed.

In this embodiment, a light-emitting device manufactured using oneembodiment of the carbazole derivative of the present invention will bedescribed with reference to FIGS. 4A and 4B. Note that FIG. 4A is a topview of the light-emitting device, and FIG. 4B is a cross-sectional viewtaken along lines A-B and C-D of FIG. 4A. Reference numerals 601, 602,and 603 denote a driver circuit portion (a source side driver circuit),a pixel portion, and a driver circuit portion (a gate side drivercircuit), respectively, which are indicated by dotted lines. Further,reference numeral 604 denotes a sealing substrate and reference numeral605 denotes a sealant. A portion surrounded by the sealant 605 is aspace 607.

Note that a lead wiring 608 is a wiring for transmitting signals to beinput into the source side driver circuit 601 and the gate side drivercircuit 603 and for receiving signals such as a video signal, a clocksignal, a start signal, and a reset signal from an FPC (flexible printedcircuit) 609 serving as an external input terminal. Although only theFPC is illustrated here, this FPC may be provided with a printed wiringboard (PWB). The light-emitting device in this specification includes,in its category, not only a light-emitting device itself but also alight-emitting device provided with an FPC or a PWB.

Next, a cross-sectional structure is described with reference to FIG.4B. The driver circuit portions and the pixel portion are formed over anelement substrate 610, but only the source side driver circuit portion601, which is a driver circuit portion, and one pixel of the pixelportion 602 are illustrated in FIG. 4B.

Note that a CMOS circuit in which an n-channel TFT 623 and a p-channelTFT 624 are formed in combination is formed in the source side drivercircuit 601. The driver circuit may be formed by a variety of CMOScircuits, PMOS circuits, or NMOS circuits. Although the driverintegrated device which has the driver circuit formed over the substrateis described in this embodiment, the driver circuit does not always haveto be formed over the substrate. It is also possible to form the drivercircuit not over the substrate but outside the substrate.

Moreover, the pixel portion 602 includes a plurality of pixels includinga switching TFT 611, a current control TFT 612, and a first electrode613 electrically connected to a drain of the current control TFT 612.Note that an insulator 614 is formed covering an end of the firstelectrode 613. Here, a positive photosensitive acrylic resin film isused for the insulator 614.

In order to improve the coverage, the insulator 614 is formed to have acurved surface with curvature at its upper or lower end portion. Forexample, in the case of using positive photosensitive acrylic for theinsulator 614, only the upper end portion of the insulator 614preferably has a curved surface with a radius of curvature (0.2 μm to0.3 μm). Further, the insulator 614 can be formed using either anegative type that becomes insoluble in an etchant by light irradiationor a positive type that becomes soluble in an etchant by lightirradiation.

A layer 616 containing a light-emitting substance and a second electrode617 are formed over the first electrode 613. Here, the first electrode613 serving as an anode is preferably formed using a material with ahigh work function. For example, a single-layer film of an ITO film, anindium tin oxide film containing silicon, an indium oxide filmcontaining zinc oxide at 2 wt % to 20 wt %, a titanium nitride film, achromium film, a tungsten film, a Zn film, a Pt film, or the like can beused. Alternatively, a stack of a titanium nitride film and a filmcontaining aluminum as its main component, a stack of three layers of atitanium nitride film, a film containing aluminum as its main component,and a titanium nitride film, or the like can be used. Note that when thefirst electrode 613 has a stacked-layer structure, the resistance can bereduced as a wiring and favorable ohmic contact can be obtained.Further, the first electrode 613 can function as an anode.

The layer 616 containing a light-emitting substance is formed by any ofa variety of methods such as an evaporation method using an evaporationmask, a droplet discharge method such as an inkjet method, a printingmethod, and a spin coating method. The layer 616 containing alight-emitting substance contains the carbazole derivative of thepresent invention which is described in Embodiment 1. As anothermaterial contained in the layer 616 containing a light-emittingsubstance, a low molecular material, a medium molecular material(including an oligomer and a dendrimer), or a high molecular materialmay be used.

Further, as a material used for the second electrode 617, which isformed over the layer 616 containing a light-emitting substance andfunctions as a cathode, a material having a low work function (Al, Mg,Li, Ca, or an alloy or a compound thereof such as MgAg, MgIn, AlLi, LiF,or CaF₂) is preferably used. In the case where light generated in thelayer 616 containing a light-emitting substance passes through thesecond electrode 617, the second electrode 617 is preferably formedusing a stack of a thin metal film having a reduced thickness and atransparent conductive film (such as ITO, indium oxide containing zincoxide at 2 wt % to 20 wt %, indium tin oxide containing silicon orsilicon oxide, or zinc oxide (ZnO)).

By attaching the sealing substrate 604 to the element substrate 610using the sealant 605, the light-emitting element 618 is provided in thespace 607 which is surrounded by the element substrate 610, the sealingsubstrate 604, and the sealant 605. Note that the space 607 is filledwith filler. The space 607 is sometimes filled with an inert gas (suchas nitrogen or argon) or the sealant 605.

Note that an epoxy-based resin is preferably used for the sealant 605.In addition, it is desirable to use a material that allows permeation ofmoisture or oxygen as little as possible. As the sealing substrate 604,a plastic substrate formed from fiberglass-reinforced plastics (FRP),polyvinyl fluoride (PVF), polyester, acrylic, or the like can be usedbesides a glass substrate or a quartz substrate.

In this manner, a light-emitting device manufactured using oneembodiment of the carbazole derivative of the present invention can beobtained.

The carbazole derivative of the present invention is a material having ahole-transporting property.

A light-emitting element with high light emission efficiency can beobtained by using a carbazole derivative of the present invention;therefore, a light-emitting element, a light-emitting device, and anelectronic device with reduced power consumption can be obtained.

Although an active matrix light-emitting device in which driving of alight-emitting element is controlled by a transistor is described inthis embodiment, a passive matrix light-emitting device may also beemployed. FIGS. 5A and 5B illustrate a passive matrix light-emittingdevice manufactured by applying the present invention. In FIGS. 5A and5B, a layer 955 containing a light-emitting substance is providedbetween an electrode 952 and an electrode 956 over a substrate 951. Anedge portion of the electrode 952 is covered with an insulating layer953. A partition layer 954 is provided over the insulating layer 953.The sidewalls of the partition layer 954 are aslope so that the distancebetween both sidewalls is gradually reduced toward the surface of thesubstrate. In other words, a cross section taken along the direction ofthe short side of the partition layer 954 is trapezoidal, and the lowerside (a side in contact with the insulating layer 953, which is one of apair of parallel sides of the trapezoidal cross section) is shorter thanthe upper side (a side not in contact with the insulating layer 953,which is the other one of the pair of parallel sides). By provision ofthe partition layer 954 in this manner, defects of the light-emittingelement due to static charge and the like can be prevented. Alight-emitting device with high reliability can be obtained also in thecase of a passive matrix light-emitting device by including alight-emitting element of the present invention.

[Embodiment 6]

In this embodiment, an electronic device of the present invention whichincludes the light-emitting device described in Embodiment 5 will bedescribed. An electronic device of the present invention includes thecarbazole derivative described in Embodiment 1, and has a displayportion with reduced power consumption.

As examples of electronic devices including a light-emitting elementformed using one embodiment of the carbazole derivative of the presentinvention, cameras such as video cameras and digital cameras, goggletype displays, navigation systems, audio reproducing devices (car audiosystems, audio component systems, and the like), computers, gamemachines, portable information terminals (mobile computers, cellularphones, portable game machines, and electronic book readers), imagereproducing devices each provided with a recording medium (specifically,devices that are capable of reproducing a recording media such as adigital versatile disc (DVD) and equipped with a display device that candisplay an image), and the like can be given. Specific examples of theseelectronic devices are illustrated in FIGS. 6A to 6E.

FIG. 6A illustrates a television device according to the presentinvention, which includes a housing 9101, a support 9102, a displayportion 9103, a speaker portion 9104, a video input terminal 9105, andthe like. In the display portion 9103 of this television device,light-emitting elements similar to those described in any of Embodiments2 to 4 are arranged in matrix. The light-emitting elements have afeature of reduced power consumption. The display portion 9103 whichincludes the light-emitting elements has a similar feature; therefore,in this television device, reduction in power consumption is achieved.Thus, a product which is more suitable for living environment can beprovided.

FIG. 6B illustrates a computer according to the present invention, whichincludes a main body 9201, a housing 9202, a display portion 9203, akeyboard 9204, an external connection port 9205, a pointing device 9206,and the like. In the display portion 9203 of this computer,light-emitting elements similar to those described in any of Embodiments2 to 4 are arranged in matrix. The light-emitting elements have afeature of reduced power consumption. The display portion 9203 whichincludes the light-emitting elements has a similar feature; therefore,in this computer, reduction in power consumption is achieved. Thus, aproduct which is more suitable for usage environment can be provided.

FIG. 6C illustrates a cellular phone according to the present invention,which includes a main body 9401, a housing 9402, a display portion 9403,an audio input portion 9404, an audio output portion 9405, operationkeys 9406, an external connection port 9407, an antenna 9408, and thelike. In the display portion 9403 of this cellular phone, light-emittingelements similar to those described in any of Embodiments 2 to 4 arearranged in matrix. The light-emitting elements have a feature ofreduced power consumption. The display portion 9403 which includes thelight-emitting elements has a similar feature; therefore, in thiscellular phone, reduction in power consumption is achieved. Thus, aproduct which is more suitable for being carried around can be provided.

FIG. 6D illustrates a camera according to the present invention, whichincludes a main body 9501, a display portion 9502, a housing 9503, anexternal connection port 9504, a remote control receiving portion 9505,an image receiving portion 9506, a battery 9507, an audio input portion9508, operation keys 9509, an eye piece portion 9510, and the like. Inthe display portion 9502 of this camera, light-emitting elements similarto those described in any of Embodiments 2 to 4 are arranged in matrix.The light-emitting elements have a feature of reduced power consumption.The display portion 9502 which includes the light-emitting elements hasa similar feature; therefore, in this camera, reduction in powerconsumption is achieved. Thus, a product which is more suitable forbeing carried around can be provided.

FIG. 6E illustrates an electronic paper according to the presentinvention, which is flexible and includes a main body 9660, a displayportion 9661 which displays images, a driver IC 9662, a receiver 9663, afilm battery 9664, and the like. The driver IC, the receiver, or thelike may be mounted using a semiconductor component. In the electronicpaper according to the present invention, the main body 9660 is formedusing a flexible material such as plastic or a film. In this electronicpaper, the display portion 9661 has light-emitting elements similar tothose described in any of Embodiments 2 to 4, which are arranged inmatrix. The light-emitting elements have features of a long lifetime andlow power consumption. The display portion 9661 which includes thelight-emitting elements has a similar feature; therefore, thiselectronic paper has high reliability and reduction in power consumptionthereof is achieved.

Furthermore, such an electronic paper is extremely light and flexibleand can be rolled into a cylinder shape as well; thus, the electronicpaper is a display device that has a great advantage in terms ofportability. The electronic device of the present invention allows adisplay medium having a large screen to be freely carried.

The electronic paper illustrated in FIG. 6E can be used as a displaymeans of a navigation system, an audio reproducing device (such as a caraudio or an audio component), a personal computer, a game machine, and aportable information terminal (such as a mobile computer, a cellularphone, a portable game machine, or an electronic book reader). Inaddition, the electronic paper illustrated in FIG. 6E can be used as ameans for mainly displaying still images for electrical home appliancessuch as a refrigerator, a washing machine, a rice cooker, a fixedtelephone, a vacuum cleaner, or a clinical thermometer; hangingadvertisements in trains; and large-sized information displays such asarrival and departure boards in railroad stations and airports.

As described above, the applicable range of a light-emitting device ofthe present invention is wide, so that this light-emitting device can beapplied to electronic devices of various fields. By using a carbazolederivative of the present invention, an electronic device having adisplay portion whose power consumption is reduced can be provided.

Moreover, a light-emitting device of the present invention can be usedas a lighting device. One mode in which the light-emitting device of thepresent invention is used as a lighting device is described withreference to FIG. 7.

FIG. 7 illustrates an example of a liquid crystal display device inwhich a light-emitting device of the present invention is used as abacklight. The liquid crystal display device illustrated in FIG. 7includes a housing 901, a liquid crystal layer 902, a backlight 903, anda housing 904. The liquid crystal layer 902 is connected to a driver IC905. The light-emitting device of the present invention is used for thebacklight 903 to which current is supplied through a terminal 906.

By using a light-emitting device of the present invention for abacklight of a liquid crystal display device, a highly reliablebacklight can be obtained. Further, a light-emitting device of thepresent invention can be applied to a lighting device of plane lightemission and can have a large area. Therefore, the backlight can have alarge area, and a liquid crystal display device having a large area canbe obtained. Furthermore, since a light-emitting device of the presentinvention is thin, the thickness of a display device can also bereduced.

FIGS. 8A and 8B each illustrate an example in which a light-emittingdevice of the present invention is used as a table lamp, which is a kindof lighting device. The table lamp illustrated in FIG. 8A includes ahousing 2001 and a light source 2002, and the table lamp illustrated inFIG. 8B includes a housing 2011 and a light source 2012. Alight-emitting device of the present invention is used as the lightsource 2002 and the light source 2012. Since power consumption of thelight-emitting device of the present invention is reduced, powerconsumption of the table lamp can also be reduced.

FIG. 9 illustrates an example in which a light-emitting device of thepresent invention is used as an indoor lighting device 3001. Since thelight-emitting device of the present invention can have a large area,the light-emitting device of the present invention can be used as alarge-area lighting device. Further, since the light-emitting device ofthe present invention is thin, the light-emitting device of the presentinvention can be used as a lighting device having a reduced thickness.In a room where a light-emitting device to which the present inventionis applied is used as the indoor lighting device 3001 in this manner, atelevision device 3002 according to the present invention, which issimilar to the one illustrated in FIG. 6A, can be placed so that publicbroadcasting and movies can be watched.

EXAMPLE 1

In this example, a synthesis method of4-(9H-carbazol-9-yl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBACzP), which is a carbazole derivative of the presentinvention and represented by the structural formula (100), will bespecifically described.

A synthesis scheme of PCBACzP is shown in (A-1).

Into a 100 mL three-neck flask were put 2.0 g (4.9 mmol) of4-(9-phenyl-9H-carbazol-3-yl)diphenylamine (PCBA), 1.6 g (4.9 mmol) of9-(4-bromophenyl)-9H-carbazole, and 2.0 g (20 mmol) of sodiumtert-butoxide, and the atmosphere in the flask was replaced withnitrogen. Then, 50 mL of toluene and 0.30 mL of tri(tert-butyl)phosphine(10 wt % hexane solution) were added to this mixture. Under reducedpressure, this mixture was degassed while being stirred. After that,0.10 g of bis(dibenzylideneacetone)palladium(0) was added to themixture. This mixture was stirred while being heated at 80° C. for 5hours to be reacted. After the reaction, toluene was added to thereaction mixture. This suspension was subjected to suction filtrationthrough Celite (produced by Wako Pure Chemical Industries, Ltd., CatalogNo. 531-16855), alumina, and Florisil (produced by Wako Pure ChemicalIndustries, Ltd., Catalog No. 540-00135), whereby a filtrate wasobtained. The obtained filtrate was washed with a saturated aqueoussodium hydrogen carbonate solution and a saturated aqueous sodiumchloride solution. After the washing, magnesium sulfate was added to anorganic layer to dry the organic layer. After the drying, this mixturewas subjected to suction filtration to give a filtrate. The obtainedfiltrate was concentrated, and purified by silica gel columnchromatography. The silica gel column chromatography was performed by,first, using a mixed solvent in which the ratio of toluene to hexane is1:9 as a developing solvent, and then using a mixed solvent in which theratio of toluene to hexane is 3:7 as another developing solvent. A solidwhich was obtained by concentrating the obtained fractions wasrecrystallized from a mixed solvent of chloroform and hexane to give 2.9g of a powdered white solid in a yield of 91%.

Sublimation purification of 1.9 g of the obtained white solid wasperformed by a train sublimation method. The sublimation purificationwas performed under a reduced pressure of 7.0 Pa and with an argon flowrate of 4 mL/min, at 330° C. for 15 hours. Thus, 1.7 g of the whitesolid was obtained in a yield of 89%.

By nuclear magnetic resonance (NMR), the compound obtained by the abovesynthesis method was identified as4-(9H-carbazol-9-yl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBACzP), which was the desired substance.

¹H NMR data of the obtained compound is shown below. ¹H NMR (CDCl₃, 300MHz): δ=7.08-7.15 (m, 1H), 7.25-7.73 (m, 28H), 8.12-8.21 (m, 3H), 8.35(s, 1H).

Further, the ¹H NMR chart is illustrated in FIGS. 12A and 12B. Note thatFIG. 12B is a chart showing an enlarged portion of FIG. 12A in the rangeof from 7.0 ppm to 8.5 ppm.

FIG. 13 and FIG. 15 show an absorption spectrum of a toluene solution ofPCBACzP and an emission spectrum thereof, respectively. FIG. 14 and FIG.16 show an absorption spectrum of a thin film of PCBACzP and an emissionspectrum thereof, respectively. The measurement of the absorptionspectrum was performed using an ultraviolet-visible spectrophotometer(V-550, manufactured by JASCO Corporation). In order to prepare samples,the solution was put to a quartz cell while the thin film was obtainedby evaporation onto a quartz substrate. The absorption spectrum of thetoluene solution of PCBACzP was obtained by subtracting the absorptionspectra of quartz and toluene from the absorption spectrum of thetoluene solution in a quartz cell, which is shown in FIG. 13. Theabsorption spectrum of the thin film of PCBACzP was obtained bysubtracting that of the quartz substrate, which is shown in FIG. 14. Ineach of FIG. 13, FIG. 14, FIG. 15, and FIG. 16, the horizontal axisrepresents wavelength (nm) and the vertical axis represents absorptionintensity (arbitrary unit). In the case of the toluene solution,absorption was observed at about 335 nm, and a maximum emissionwavelength was 393 nm (excitation wavelength: 335 nm). Further, in thecase of the thin film, absorption was observed at about 334 nm, and amaximum emission wavelength was 411 nm (excitation wavelength: 361 nm).

Further, the HOMO level and LUMO level of PCBACzP in a state of a thinfilm were measured. The value of the HOMO level was obtained byconversion of the value of the ionization potential measured with aphotoelectron spectrometer (AC-2, manufactured by RIKEN KEIKI Co., Ltd.)in the atmosphere into a negative value. In addition, the value of theLUMO level was obtained in such a manner that the absorption edge wasobtained from Tauc plot, with an assumption of direct transition, usingdata on the absorption spectrum of the thin film of PCBACzP which wasshown in FIG. 14, and added as an optical energy gap to the value of theHOMO level. The results show that the HOMO level, energy gap, and LUMOlevel of PCBACzP are −5.44 eV, 3.30 eV, and −2.14 eV, respectively.

Further, the oxidation-reduction characteristics of PCBACzP weremeasured. The oxidation-reduction characteristics were measured bycyclic voltammetry (CV) measurement. Further, an electrochemicalanalyzer (ALS model 600A, manufactured by BAS Inc.) was used for themeasurement.

As for a solution used in the CV measurement, dehydrateddimethylformamide (DMF, manufactured by Sigma-Aldrich Corp., 99.8%,catalog number: 22705-6) was used as a solvent. Tetra-n-butylammoniumperchlorate (n-Bu₄NClO₄, manufactured by Tokyo Chemical Industry Co.,Ltd., catalog number: T0836), which was a supporting electrolyte, wasdissolved in the solvent such that the concentration of thetetra-n-butylammonium perchlorate was 100 mmol/L. Moreover, the objectto be measured was dissolved such that the concentration thereof was setto 1 mmol/L. A platinum electrode (manufactured by BAS Inc., PTEplatinum electrode) was used as a working electrode, a platinumelectrode (manufactured by BAS Inc., Pt counter electrode for VC-3, (5cm)) was used as an auxiliary electrode, and an Ag/Ag⁺ electrode(manufactured by BAS Inc., RE-7 reference electrode for nonaqueoussolvent) was used as a reference electrode. The measurement was carriedout at room temperature.

The oxidation reaction characteristics of PCBACzP were measured asfollows. A scan in which the potential of the working electrode withrespect to the reference electrode was changed to 0.90 V from −0.075 Vand then the potential was changed to −0.077 V from −0.90 V was set asone cycle, and 100 cycle measurements were performed. Note that thescanning speed of the CV measurement was set at 0.1 V/s.

The reduction reaction characteristics of PCBACzP were measured asfollows. A scan in which the potential of the working electrode withrespect to the reference electrode was changed to −3.00 V from −1.11 Vand then the potential was changed to −1.11 V from −3.00 V was set asone cycle, and 100 cycle measurements were performed. Note that thescanning speed of the CV measurement was set at 0.1 V/s.

FIG. 17 shows CV measurement results on the oxidation reactioncharacteristics of PCBACzP and FIG. 18 shows CV measurement results onthe reduction reaction characteristics thereof. In each of FIG. 17 andFIG. 18, the horizontal axis represents potential (V) of the workingelectrode with respect to the reference electrode, and the vertical axisrepresents value of a current (μA) flowing between the working electrodeand the auxiliary electrode. According to FIG. 17, a current indicatingoxidation was observed at around +0.54 V (vs. Ag/Ag⁺ electrode).

EXAMPLE 2

In this example, a synthesis method of4-(9H-carbazol-9-yl)-4′-phenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBiCP), which is a carbazole derivative of the presentinvention and represented by the structural formula (123), will bespecifically described.

A synthesis scheme of PCBBiCP is shown in (B-1).

Into a 100 mL three-neck flask were put 2.0 g (4.1 mmol) of4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)diphenylamine (PCBBi), 1.3 g (4.1mmol) of N-(4-bromophenyl)carbazole, and 2.0 g (20 mmol) of sodiumtert-butoxide, and the atmosphere in the flask was replaced withnitrogen. Then, 50 mL of toluene and 0.30 mL of tri(tert-butyl)phosphine(10 wt % hexane solution) were added to this mixture. Under reducedpressure, this mixture was degassed while being stirred. After that,0.10 g of bis(dibenzylideneacetone)palladium(0) was added to themixture. This mixture was stirred while being heated at 80° C. for 5hours to be reacted. After the reaction, toluene was added to thereaction mixture. This suspension was subjected to suction filtrationthrough Celite (produced by Wako Pure Chemical Industries, Ltd., CatalogNo. 531-16855), alumina, and Florisil (produced by Wako Pure ChemicalIndustries, Ltd., Catalog No. 540-00135), whereby a filtrate wasobtained. The obtained filtrate was washed with a saturated aqueoussodium hydrogen carbonate solution and a saturated aqueous sodiumchloride solution. After the washing, magnesium sulfate was added to anorganic layer to dry the organic layer. After the drying, this mixturewas subjected to suction filtration to give a filtrate. The obtainedfiltrate was concentrated, and purified by silica gel columnchromatography. The silica gel column chromatography was performed by,first, using a mixed solvent in which the ratio of toluene to hexane is1:9 as a developing solvent, and then using a mixed solvent in which theratio of toluene to hexane is 3:7 as another developing solvent. A solidwhich was obtained by concentrating the obtained fractions wasrecrystallized from a mixed solvent of chloroform and hexane to give 2.1g of a powdered white solid in a yield of 70%.

Sublimation purification of 1.0 g of the obtained white solid wasperformed by a train sublimation method. The sublimation purificationwas performed under a reduced pressure of 7.0 Pa and with an argon flowrate of 4 mL/min, at 350° C. for 15 hours. Thus, 0.85 g of the whitesolid was obtained in a yield of 85%.

By nuclear magnetic resonance (NMR), the compound obtained by the abovesynthesis method was identified as4-(9H-carbazol-9-yl)-4′-phenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBiCP), which was the desired substance.

¹H NMR data of the obtained compound is shown below. ¹H NMR (CDCl₃, 300MHz): δ=7.26-7.75 (m, 33H), 8.13-8.23 (m, 3H), 8.37 (m, 1H).

Further, the ¹H NMR chart is illustrated in FIGS. 19A and 19B. Note thatFIG. 19B is a chart showing an enlarged portion of FIG. 19A in the rangeof from 7.0 ppm to 8.5 ppm.

FIG. 20 and FIG. 22 show an absorption spectrum of a toluene solution ofPCBBiCP and an emission spectrum thereof, respectively. FIG. 21 and FIG.23 show an absorption spectrum of a thin film of PCBBiCP and an emissionspectrum thereof, respectively. The measurement of the absorptionspectrum was performed using an ultraviolet-visible spectrophotometer(V-550, manufactured by JASCO Corporation). In order to prepare samples,the solution was put to a quartz cell while the thin film was obtainedby evaporation onto a quartz substrate. The absorption spectrum of thetoluene solution of PCBBiCP was obtained by subtracting the absorptionspectra of quartz and toluene from the absorption spectrum of thetoluene solution in a quartz cell, which is shown in FIG. 20. Theabsorption spectrum of the thin film of PCBBiCP was obtained bysubtracting that of the quartz substrate, which is shown in FIG. 21. Ineach of FIG. 20, FIG. 21, FIG. 22, and FIG. 23, the horizontal axisrepresents wavelength (nm) and the vertical axis represents absorptionintensity (arbitrary unit). In the case of the toluene solution,absorption was observed at about 338 nm, and a maximum emissionwavelength was 394 nm (excitation wavelength: 338 nm). Further, in thecase of the thin film, absorption was observed at about 345 nm, and amaximum emission wavelength was 424 nm (excitation wavelength: 353 nm).

Further, the HOMO level and LUMO level of PCBBiCP in a state of a thinfilm were measured. The value of the HOMO level was obtained byconversion of the value of the ionization potential measured with aphotoelectron spectrometer (AC-2, manufactured by RIKEN KEIKI Co., Ltd.)in the atmosphere into a negative value. In addition, the value of theLUMO level was obtained in such a manner that the absorption edge wasobtained from Tauc plot, with an assumption of direct transition, usingdata on the absorption spectrum of the thin film of PCBBiCP which wasshown in FIG. 21, and added as an optical energy gap to the value of theHOMO level. The results show that the HOMO level, energy gap, and LUMOlevel of PCBBiCP are −5.41 eV, 3.23 eV, and −2.18 eV, respectively.

Further, the oxidation-reduction characteristics of PCBBiCP weremeasured. The oxidation-reduction characteristics were measured bycyclic voltammetry (CV) measurement. Further, an electrochemicalanalyzer (ALS model 600A, manufactured by BAS Inc.) was used for themeasurement.

As for a solution used in the CV measurement, dehydrateddimethylformamide (DMF, manufactured by Sigma-Aldrich Corp., 99.8%,catalog number: 22705-6) was used as a solvent. Tetra-n-butylammoniumperchlorate (n-Bu₄NClO₄, manufactured by Tokyo Chemical Industry Co.,Ltd., catalog number: T0836), which was a supporting electrolyte, wasdissolved in the solvent such that the concentration of thetetra-n-butylammonium perchlorate was 100 mmol/L. Moreover, the objectto be measured was dissolved such that the concentration thereof was setto 1 mmol/L. A platinum electrode (manufactured by BAS Inc., PTEplatinum electrode) was used as a working electrode, a platinumelectrode (manufactured by BAS Inc., Pt counter electrode for VC-3, (5cm)) was used as an auxiliary electrode, and an Ag/Ag⁺ electrode(manufactured by BAS Inc., RE-7 reference electrode for nonaqueoussolvent) was used as a reference electrode. The measurement was carriedout at room temperature.

The oxidation reaction characteristics of PCBBiCP were measured asfollows. A scan in which the potential of the working electrode withrespect to the reference electrode was changed to 1.00 V from −0.029 Vand then the potential was changed to −0.031 V from 1.00 V was set asone cycle, and 100 cycle measurements were performed. Note that thescanning speed of the CV measurement was set at 0.1 V/s.

The reduction reaction characteristics of PCBBiCP were measured asfollows. A scan in which the potential of the working electrode withrespect to the reference electrode was changed to −3.00 V from −1.02 Vand then the potential was changed to −1.02 V from −3.00 V was set asone cycle, and 100 cycle measurements were performed. Note that thescanning speed of the CV measurement was set at 0.1 V/s.

FIG. 24 shows CV measurement results on the oxidation reactioncharacteristics of PCBBiCP and FIG. 25 shows CV measurement results onthe reduction reaction characteristics thereof. In each of FIG. 24 andFIG. 25, the horizontal axis represents potential (V) of the workingelectrode with respect to the reference electrode, and the vertical axisrepresents value of a current (μA) flowing between the working electrodeand the auxiliary electrode. According to FIG. 24, a current indicatingoxidation was observed at around +0.56 V (vs. Ag/Ag⁺ electrode).

EXAMPLE 3

In this example, a light-emitting element of one embodiment of thepresent invention will be described with reference to FIG. 10.

The element structures of a comparative light-emitting element, alight-emitting element 1, and a light-emitting element 2 which weremanufactured in this example are shown in Table 1. In Table 1, themixture ratios are all represented in weight ratios.

TABLE 1 first first second third electrode layer layer layer 2102 21032104 2105 comparative ITSO NPB:MoOx NPB CzPA:PCBAPA light-emitting 110nm (=4:1) 10 nm (=1:0.1) element 50 nm 30 nm light-emitting ITSONPB:MoOx PCBACzP CzPA:PCBAPA element 1 110 nm (=4:1) 10 nm (=1:0.1) 50nm 30 nm light-emitting ITSO NPB:MoOx PCBBiCP CzPA:PCBAPA element 2 110nm (=4:1) 10 nm (=1:0.1) 50 nm 30 nm fifth second fourth layer layerelectrode 2106 2107 2108 comparative Alq Bphen LiF Al light-emitting 10nm 20 nm 1 nm 200 nm element light-emitting Alq Bphen LiF Al element 110 nm 20 nm 1 nm 200 nm light-emitting Alq Bphen LiF Al element 2 10 nm20 nm 1 nm 200 nm *mixture ratios are all represented in weight ratios.

Methods for manufacturing light-emitting elements of this example aredescribed below.

In the formation of each of the comparative light-emitting element, thelight-emitting element 1, and the light-emitting element 2, indium tinoxide containing silicon oxide (ITSO) was deposited over a glasssubstrate 2101 by a sputtering method, whereby a first electrode 2102was formed. The thickness of the first electrode 2102 was 110 nm and theelectrode area was 2 mm×2 mm.

Next, the substrate over which the first electrode was formed was fixedto a substrate holder provided in a vacuum evaporation apparatus so thata surface of the substrate on which the first electrode was formed faceddownward. The pressure was reduced to about 10⁻⁴ Pa, and then4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) andmolybdenum(VI) oxide were co-evaporated on the first electrode 2102,whereby a layer containing a composite material of an organic compoundand an inorganic compound was formed as a first layer 2103. Thethickness of the first layer 2103 was 50 nm and the weight ratio of NPBto molybdenum(VI) oxide was adjusted to be 4:1 (=NPB:molybdenum oxide).Note that co-evaporation is an evaporation method in which evaporationis performed at the same time from a plurality of evaporation sources inone treatment chamber.

Next, as for the comparative light-emitting element used as acomparative example, NPB was evaporated to a thickness of 10 nm, wherebya second layer 2104 was formed as a hole-transporting layer.

As for the light-emitting element 1, PCBACzP synthesized in Example 1was evaporated to a thickness of 10 nm, whereby a second layer 2104 wasformed as a hole-transporting layer.

As for the light-emitting element 2, PCBBiCP, which was synthesized inExample 2, was evaporated to a thickness of 10 nm, whereby a secondlayer 2104 was formed as a hole-transporting layer.

Next, in the formation of each of the comparative light-emittingelement, the light-emitting element 1, and the light-emitting element 2,CzPA and4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA) were co-evaporated onto the second layer 2104 sothat the weight ratio of CzPA to PCBAPA was 1:0.1 (=CzPA:PCBAPA),whereby a third layer 2105 was formed as a light-emitting layer. Thethickness of the third layer 2105 was 30 nm.

Next, in the formation of each of the comparative light-emittingelement, the light-emitting element 1, and the light-emitting element 2,Alq was evaporated onto the third layer 2105 to a thickness of 10 nm,and then Bphen was evaporated to a thickness of 20 nm to form a stackedlayer, whereby a fourth layer 2106 was formed as anelectron-transporting layer. Further, lithium fluoride (LiF) wasevaporated onto the fourth layer 2106 to a thickness of 1 nm, whereby afifth layer 2107 was formed as an electron-injecting layer. Lastly,aluminum was evaporated to a thickness of 200 nm as a second electrode2108 which functions as a cathode. Accordingly, the comparativelight-emitting element, the light-emitting element 1, and thelight-emitting element 2 of this example were obtained. Note that in allof the above evaporation steps, a resistance heating method was used. Inaddition, structural formulae of NPB, CzPA, PCBAPA, Alq, and Bphen areshown below.

The comparative light-emitting element, the light-emitting element 1,and the light-emitting element 2 obtained in the above manner weresealed in a glove box under a nitrogen atmosphere without being exposedto the atmosphere. After that, the operating characteristics of thecomparative light-emitting element, the light-emitting element 1, andthe light-emitting element 2 were measured. The measurement wasperformed at room temperature (in the atmosphere in which thetemperature was kept at 25° C.).

FIG. 26 shows the current density-luminance characteristics of thelight-emitting elements, FIG. 27 shows the voltage-luminancecharacteristics thereof, and FIG. 28 shows the luminance-currentefficiency characteristics thereof. In addition, FIG. 29 shows theemission spectrum at a current of 1 mA. According to FIG. 29, it wasfound that favorable blue light emission of PCBAPA having a peak ataround 457 nm was obtained from each of the comparative light-emittingelement, the light-emitting element 1, and the light-emitting element 2.

The comparative light-emitting element provided blue light emissionwhere the CIE chromaticity coordinates were (x=0.15, y=0.17) when theluminance was 1106 cd/m². Further, the current efficiency, externalquantum efficiency, voltage, current density, and power efficiency at aluminance of 1106 cd/m² were 4.29 cd/A, 3.2%, 4.0 V, 25.8 mA/cm², and3.37 lm/W, respectively.

The light-emitting element 1 provided favorable blue light emissionwhere the CIE chromaticity coordinates were (x=0.15, y=0.17) when theluminance was 916 cd/m². Further, the current efficiency, externalquantum efficiency, voltage, current density, and power efficiency at aluminance of 916 cd/m² were 5.87 cd/A, 4.4%, 3.8 V, 15.6 mA/cm², and4.85 lm/W, respectively.

The light-emitting element 2 provided favorable blue light emissionwhere the CIE chromaticity coordinates were (x=0.15, y=0.17) when theluminance was 1037 cd/m². Further, the current efficiency, externalquantum efficiency, voltage, current density, and power efficiency at aluminance of 1037 cd/m² were 6.34 cd/A, 4.6%, 3.8 V, 16.4 mA/cm², and5.24 lm/W, respectively.

The light-emitting element 1 was formed using PCBACzP, which is oneembodiment of the present invention, for the hole-transporting layer,and the light-emitting element 2 was formed using PCBBiCP, which is oneembodiment of the present invention, for the hole-transporting layer. Itcan be seen that these light-emitting elements each have improved lightemission efficiency as compared with the comparative light-emittingelement used as a comparative example.

It was confirmed that one embodiment of the light-emitting element ofthe present invention had characteristics as a light-emitting elementwith high light emission efficiency and fully functioned.

EXAMPLE 4

Since4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA), which is used in Example 3, is a novelsubstance, a synthesis method thereof is described below.

A synthesis scheme of PCBAPA is shown in the following (X-1).

Into a 300 mL three-neck flask were put 7.8 g (12 mmol) of9-(4-bromophenyl)-10-phenylanthracene, 4.8 g (12 mmol) of PCBA, and 5.2g (52 mmol) of sodium tert-butoxide, and the atmosphere in the flask wasreplaced with nitrogen. To the mixture were added 60 mL of toluene and0.30 mL of tri(tert-butyl)phosphine (10 wt % hexane solution). Then, 60mL of toluene and 0.30 mL of tri(tert-butyl)phosphine (10 wt % hexanesolution) were added to this mixture. Under reduced pressure, thismixture was degassed while being stirred. After that, 136 mg (0.24 mmol)of bis(dibenzylideneacetone)palladium(0) was added to the mixture. Thismixture was stirred at 100° C. for 3 hours. After the stirring, about 50mL of toluene was added to this mixture. The mixture was subjected tosuction filtration through Celite (produced by Wako Pure ChemicalIndustries, Ltd., Catalog No. 531-16855), alumina, and Florisil(produced by Wako Pure Chemical Industries, Ltd., Catalog No.540-00135). The obtained filtrate was condensed to give a yellow solid.This solid was recrystallized from toluene/hexane to give 6.6 g of alight yellow powder PCBAPA, which was the desired substance, in a yieldof 75%.

¹H NMR data of the light yellow powder which was obtained by the abovesynthesis method was measured. The measurement data are shown below. Themeasurement results show that PCBAPA was obtained.

¹H NMR (CDCl₃, 300 MHz): δ=7.09-7.14 (m, 1H), 7.28-7.72 (m, 33H), 7.88(d, J=8.4 Hz, 2H), 8.19 (d, J=7.2 Hz, 1H), 8.37 (d, J=1.5 Hz, 1H).

This application is based on Japanese Patent Application serial no.2009-085233 filed with Japan Patent Office on Mar. 31, 2009, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. A light-emitting element comprising: a firstelectrode; a layer over the first electrode; a light-emitting layer overthe layer; and a second electrode over the light-emitting layer, whereinthe layer comprises a carbazole derivative represented by a generalformula (1),

wherein Ar¹ represents a substituted or unsubstituted aryl group having6 to 10 carbon atoms which form a ring; α and β independently representa substituted or unsubstituted arylene group having 6 to 12 carbon atomswhich form a ring; R¹ represents an alkyl group having 1 to 4 carbonatoms or a substituted or unsubstituted aryl group having 6 to 10 carbonatoms which form a ring; and R¹¹ to R¹⁷ and R²¹ to R²⁸ independentlyrepresent hydrogen, an alkyl group having 1 to 4 carbon atoms, or asubstituted or unsubstituted aryl group having 6 to 10 carbon atomswhich form a ring.
 2. A light-emitting device comprising: thelight-emitting element according to claim 1; and means for controllingthe light-emitting element.
 3. An electronic device wherein thelight-emitting device according to claim 2 is provided in a displayportion.
 4. A lighting device comprising the light-emitting deviceaccording to claim
 2. 5. A light-emitting element comprising: a firstelectrode; a hole-transporting layer over the first electrode; alight-emitting layer over the hole-transporting layer; and a secondelectrode over the light-emitting layer, wherein the hole-transportinglayer comprises a carbazole derivative represented by a general formula(1),

wherein Ar¹ represents a substituted or unsubstituted aryl group having6 to 10 carbon atoms which form a ring; α and β independently representa substituted or unsubstituted arylene group having 6 to 12 carbon atomswhich form a ring; R¹ represents an alkyl group having 1 to 4 carbonatoms or a substituted or unsubstituted aryl group having 6 to 10 carbonatoms which form a ring; and R¹¹ to R¹⁷ and R²¹ to R²⁸ independentlyrepresent hydrogen, an alkyl group having 1 to 4 carbon atoms, or asubstituted or unsubstituted aryl group having 6 to 10 carbon atomswhich form a ring.
 6. A light-emitting device comprising: thelight-emitting element according to claim 5; and means for controllingthe light-emitting element.
 7. An electronic device wherein thelight-emitting device according to claim 6 is provided in a displayportion.
 8. A lighting device comprising the light-emitting deviceaccording to claim
 6. 9. A light-emitting element comprising: a firstelectrode; a hole-injecting layer over the first electrode; alight-emitting layer over the hole-injecting layer; and a secondelectrode over the light-emitting layer, wherein the hole-injectinglayer comprises a carbazole derivative represented by a general formula(1),

wherein Ar¹ represents a substituted or unsubstituted aryl group having6 to 10 carbon atoms which form a ring; α and β independently representa substituted or unsubstituted arylene group having 6 to 12 carbon atomswhich form a ring; R¹ represents an alkyl group having 1 to 4 carbonatoms or a substituted or unsubstituted aryl group having 6 to 10 carbonatoms which form a ring; and R¹¹ to R¹⁷ and R²¹ to R²⁸ independentlyrepresent hydrogen, an alkyl group having 1 to 4 carbon atoms, or asubstituted or unsubstituted aryl group having 6 to 10 carbon atomswhich form a ring.
 10. A light-emitting device comprising: thelight-emitting element according to claim 9; and means for controllingthe light-emitting element.
 11. An electronic device wherein thelight-emitting device according to claim 10 is provided in a displayportion.
 12. A lighting device comprising the light-emitting deviceaccording to claim
 10. 13. The light-emitting device according to claim1, wherein the light-emitting layer is in contact with the layer.